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On the basis of the biochemical characteristics it was expected, that Bacillus phytase might be able to act along the small intestine while all other phytases used in this study may act probably only during the passage through the stomach due to their pH optima between 4.5 and 5.5. However, these enzymes differ in their proteolytic stability in so far as Klebsiella and E. coli phytases are more stable than the Aspergillus phytase, therefore, they would be inactivated in stomach more slowly. That means E. coli and Klebsiella phytases would be able to be active in the stomach for a longer time. Because Bacillus phytase was inactivated during incubation with stomach content by 70% this inactivation was taken into consideration by increasing the supply of this enzyme to 700 U/kg feed instead of 500 U/kg. The results of the animal trial indicated that all the phytases were effective in improving the bioavailability of phytate phosphorus in broiler chickens. The differences between the Aspergillus phytase and the bacterial phytases were in this study only marginal. However, in this study it was shown that a phytase with the small intestine as the main site of action is similarly effective as phytases acting mainly in the stomach. Therefore, the combination of both types of enzymes might act additive in release of phytate P. In our study the combination of the E. coli phytase with the Bacillus phytase resulted in a nonsignificant higher phosphorus utilization compared to all other enzymes (58 vs. 54%). The idea of combining phytases with different properties acting in different sections of the digestive tract in order to achieve synergistic effects in phosphorus liberation seems worth to be followed in future research.
It could be concluded that all enzymes improved the phosphorus utilization (P-balance). This work indicated the feasibility of utilization the combination of (Bacillus and E. coli phytases) to increase the availability of phytate phosphorus.